Messages in this thread | | | Date | Wed, 02 Jan 2008 18:25:21 -0600 | From | Robert Hancock <> | Subject | Re: SATA kernel-buffered read VERY slow (not raid, Promise TX300 card); 2.6.23.1(vanilla) |
| |
Linda Walsh wrote: > Alan Cox wrote: >>> rate began falling; at 128k block-reads-at-a-time or larger, it drops >>> below >>> 20MB/s (only on buffered SATA). >> >> Try disabling NCQ - see if you've got a drive with the 'NCQ = no >> readahead' flaw. > --- > I'm not aware, off hand, how to disable NCQ. I haven't had any > NCQ- or SATA- capable disks before a few weeks ago.
See here:
http://linux-ata.org/faq.html#ncq
> >>> The only way I could tell before was using hdparm to read the >>> parameters. Since that doesn't work, it's hard to tell if they >>> are set correctly... >> >> hdparm supports identify to read modes on drives with libata. The one >> thing you cannot do is force modes right now. >> >>> More importantly, how does one set parameters for acoustic and power >>> saving parameters? Some of my disks are used as 'backup' devices for my >> >> hdparm or blktool > ---- > > I have hdparm-v7.7. There are some areas where it shows information, > but areas where it > does not work jump out and lead me to suspect whether or not areas > that don't give explicit "ERROR" messages are presenting valid info. > > Problem areas (using hdparm, disk=Seagate Barracuda 16MB cache, model= > ST3750640AS): > 1) The drives current 'multicount' setting isn't readable or settable. > param "-i" shows "?16?" (with question marks around 16) and "-I" simply > shows "?" for the current setting. Attempting to <read|set> it: > "HDIO_<GET|SET>_MULTCOUNT failed: Inappropriate ioctl for device"
I don't think you can get or get the multi count currently, it just uses the best supported value.
> 2) Drive Advanced Power Management setting("-B") (write-only): > "HDIO_DRIVE_CMD failed: Input/output error" > 3) Drive Acoustic ("-M"), read = " acoustic = not supported", > write = " HDIO_DRIVE_CMD:ACOUSTIC failed: Input/output error" > Note: drive detailed info from "-I" says: > "Recommended acoustic management value: 254, current value: 0" > (i.e. - there seems to be no way to set recommended value)
Not sure about these ones.. Does anything show up in dmesg when you do this?
> 4) 32-bit IO setting ("-c") (don't know if this important given the disk's > raw-read speed, it may be meaningless for SATA) > "IO_support = 0 (default 16-bit)"* > *
This setting is not meaningful for anything using DMA.
> FWIW -- the spindown/standby timeout ("S") does seem to work. > >>> other computers. With the ATA disks, they were kept "spun down" when >>> not >>> being used (only used, 'normally', in early AM hours). >> >> Well for backup devices you can use the fact SATA is hot/warm plug. > --- > I don't follow. It is an internal drive. Are their software "logically > unplug" commands that automatically re-"plug-in" the drive on access > and spin it back up like the spindown/standby timeout does? Or were > you referring to SATA's general hot/warm plug ability (if my hardware > setup, drive-slots, etc, permitted removability)?
I think they were referring to physically hotplugging the drive. This is more practical if you have a removable drive caddy, or if the drive is hooked up through eSATA.
-- Robert Hancock Saskatoon, SK, Canada To email, remove "nospam" from hancockr@nospamshaw.ca Home Page: http://www.roberthancock.com/
| |